This invention relates to a pneumatically-operated diaphragm pump utilized in a Post-mix beverage syrup dispensing system and more specifically to a reciprocating pump including a spring actuated reversing means for reversing the direction of a reciprocating pump at the end of its respective strokes.
Diaphragm pumps are widely used particularly for pumping liquid solutions and highly viscous materials and are frequently used under conditions such that the viscosity of the fluid being pumped, the head of the suction side of the pump and the back pressure on the pump discharge may all vary as conditions under which the pump is operating vary. The speed of such pumps has generally been controlled by inserting an adjustable valve in the air line leading to the pump. However, this approach requires that the operation of the pump be kept under continuous observation and the valve adjusted to suit varying conditions, otherwise the speed of the pump will vary substantially depending upon the conditions of operation. For example, if the back pressure on the pump should increase or decrease for any particular reason, or if the viscosity of the liquid being pumped should vary, then the speed of operation and the quantity of liquid being pumped per unit of time will accordingly be affected. Therefore, it is highly desirable that the pump be controlled such that it operates at a substantially constant speed under varying conditions. Furthermore, it is essential that the entire pumping cycle be completed so as to ensure continuous delivery of the medium being pumped at a constant consistency or concentration. In order to ensure the latter, means have been suggested such as disclosed in U.S. Pat. No. 4,008,984 wherein opposed coil springs are provided for assisting the respective valve member in the completion of its pumping cycle. The coil compression springs of identical force under the pressurized gas system assist in completion of the pumping cycle first in one direction, and then by asserting a positive reversing effect when either of the springs becomes fully compressed. Although providing a reversing mechanism for the double acting pump disclosed, there are inherent disadvantages with such a system. For example, if for some reason the pressurized system is effected in such a way that a back pressure is created or established so as to inhibit or reverse the pumping cycle before it is completed, there is no means for overcoming the undesirable effect, and the fully compressed state of the spring is not reached. Thus, it is possible that the pumping cycle could be reversed regardless of the presence of the compression springs, before the cycle is completed, thus effecting the efficiency, if not the complete purpose, of the reciprocating pump.
It is, therefore, an object of the present invention to provide a reciprocating diaphragm pump for delivering, under constant pressure, syrup to a Post-mix beverage dispensing system which will overcome the above noted disadvantages.
It is a further object of the present invention to provide a double-acting reciprocating pump for syrup in a Post-mix beverage dispensing system wherein a reversing means is provided for reversing the direction of the pump at the end of each respective stroke.
Yet, still a further object of the present invention is to provide a gas-operated diaphragm pump including a specialized valve, actuated by a springloaded member attached to a common shaft, which alternates the supply of pressurized gas to the respective diaphragms.
It is still a further object of the present invention to provide a double-acting reciprocating pneumatic pump for dispensing syrup to a dispensing outlet wherein the pump cycle reversing system includes a snap-acting reversing means which ensures the completion of the pumping cycle and precludes the sticking of the pneumatic reversing mechanism in an intermediate position.
Yet, still another object of the present invention is to provide a pneumatic double-acting reciprocating pump having a reversing system which includes a valve, a valve actuating member, and a snap-acting spring member which reliably directs the supply of pressurized gas to the surface of either one of the two diaphragms in a cyclic manner.
A further object of the present invention is to provide a reciprocating pneumatic diaphragm pump including a reversing means which allows for the dispersing of fluid from either one of two diaphragm chambers at the respective ends of the pump in a systematic, controlled manner.
Other objects and further scope of applicability of the present invention will become more apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and accompanying drawings, while indicating preferred embodiments of the present invention, are given by way of illustration only since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. Any such changes and modifications should be considered to be within the scope of this invention.